To save channel capacity and storage space, considering that human ears are less sensitive to high frequency information than to low frequency information of an audio signal, the high frequency information is usually cut, resulting in decreased audio quality. Therefore, a bandwidth extension technology is introduced to reconstruct the cut high frequency information, so as to improve the audio quality. As the rate increases, with coding performance ensured, a wider band of a high frequency part that can be coded enables a receiver to obtain a wider-band and higher-quality audio signal.
In the foregoing solution, the input audio signal restored by the decoder may be apt to have relatively severe signal distortion.